1. Field of the Invention
The present invention relates to an endotoxin adsorption system, a method for adsorbing endotoxin using an endotoxin system, and an endotoxin adsorber including the system.
2. Description of the Prior Art
One of the most numerous and dominant agents causing inflammation from bacterial infection is endotoxin which is present on the surface of Gram-negative bacteria. Due to the effect of endotoxin, production of various cytokines and activated complements are promoted.
For example, in septicemia, endotoxin is produced by a bacterial infection, resulting in systemic inflammation. When inflammation proceeds, a shock symptom (septic shock) is caused, which may result in an organic disorder (organic deficiency) and a critical condition such as a multi-organic deficiency.
Examples of therapeutic methods for septicemia include administration of antibiotics for preventing the infection, administration of .gamma.-globulin for activating resistance to the infection, and the like. Irrespective of these therapeutic methods, septicemia still shows a high death rate. Therefore, it is desirable from a medical point of view that the endotoxin causing the septicemia is removed from a body fluid.
It is known to use an adsorbent for the purpose of removing endotoxin. For example, Japanese Patent Publication No. 1-16389 discloses a material in which polymyxin known as an antidote for endotoxin is immobilized onto an appropriate carrier. Japanese Patent Publication No. 3-35974 discloses an adsorbent in which basic nitrogen functional groups and polymyxin are bound to a vinyl polymer. This adsorbent decomposes endotoxin with polymyxin and allows the decomposed product to adsorb to the nitrogen functional group. However, some steps are required for preparing such adsorbent and polymyxin used as an antidote is very expensive. Japanese Laid-Open Patent Publication No. 6-211900 discloses an adsorption material in which a polyanion polymer is bound to a carrier (e.g., porous glass, silica gel coated with a porous organic polymer, and cross-linked carbohydrate) having appropriate pore diameter and molecule excluding range. However, the effect of this adsorption material to adsorb endotoxin is small. The inventors of the present invention disclose in Japanese Laid-Open Patent Publication No. 8-173803 that a styrene-divinylbenzene copolymer with a sulfo group introduced thereto is effective as an appropriate carrier for removing endotoxin. However, in the case where this carrier is utilized for actual treatment in extracorporal circulation under the condition that the carrier having sodium as a counter ion is used alone, there is a possibility that the carrier not only removes endotoxin from a body fluid but also decreases the concentration of cations other than sodium. Thus, further improvement has been desired.